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Abstract
Objective To analyze differences in functional brain images collected in patients with type 2 and type 1 narcolepsy compared to normal controls and the relationship among brain images, objective neuropsychologic tests, and sleep findings.
Methods Data collection included comprehensive clinical investigation, study of sleep/wake with actigraphy, polysomnography, Multiple Sleep Latency Test, human leukocyte antigen typing, 18F-fluorodeoxyglucose PET, and cognitive tests obtained from 29 patients with type 2 narcolepsy, 104 patients with type 1 narcolepsy, and 26 sex- and age-matched normal control individuals. Conners’ Continuous Performance Test (CPT II) and Wisconsin Card-Sorting Task were performed simultaneously with the FDG-PET examination. After analyses of variance, data between patients with type 1 and type 2 narcolepsy were compared by post hoc analysis, and correlation between functional brain imaging findings and results of neurocognitive tests was obtained.
Results All patients with narcolepsy presented with at least 2 sleep-onset REM periods (SOREMP) and subjective sleepiness. Patients with type 2 narcolepsy compared to patients with type 1 narcolepsy had significantly less SOREMP, longer mean sleep latencies, and lower body mass indexes, apnea-hypopnea indexes, and frequency of human leukocyte antigen DQ-Beta1*0602. In patients with type 2 narcolepsy, FDG-PET studies showed significantly less hypermetabolism in the fusiform gyrus, striatum, hippocampus, thalamus, basal ganglia, and cerebellum than in patients with type 1 narcolepsy, and significantly less hypometabolism in the regions of frontal lobe, posterior cingulum, angular gyrus, and part of the parietal lobe; these changes were associated with fewer errors on the CPT.
Conclusion Young patients with type 2 narcolepsy have fewer clinical impairments and less distinct brain functional abnormalities than patients with type 1 narcolepsy, who are significantly more affected.
Glossary
- ANOVA=
- analysis of variance;
- CPT II=
- Conners' Continuous Performance Test;
- DLPFC=
- dorsolateral prefrontal cortex;
- DMN=
- default mode network;
- ESS=
- Epworth Sleepiness Scale;
- FDG=
- 18F-fluorodeoxyglucose;
- HLA=
- human leukocyte antigen;
- ICSD-3=
- International Classification of Sleep Disorders–3;
- MSLT=
- Multiple Sleep Latency Test;
- OSA=
- obstructive sleep apnea;
- PDSS=
- Pediatric Daytime Sleepiness Scale;
- PSG=
- polysomnography;
- RT=
- reaction time;
- SOREMP=
- sleep-onset REM periods;
- SUVR=
- standard uptake value ratio;
- TPN=
- task-positive network;
- WCST=
- Wisconsin Card-Sorting Test
Footnotes
↵* These authors contributed equally to this work.
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Patient Page: NPub.org/patient
- Received December 3, 2016.
- Accepted in final form January 4, 2018.
- © 2018 American Academy of Neurology
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